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- "use strict";
- module.exports = {
- meta: {
- type: "suggestion",
- docs: {
- description: "Disallow negated conditions",
- recommended: false,
- url: "https://eslint.org/docs/latest/rules/no-negated-condition"
- },
- schema: [],
- messages: {
- unexpectedNegated: "Unexpected negated condition."
- }
- },
- create(context) {
-
- function hasElseWithoutCondition(node) {
- return node.alternate && node.alternate.type !== "IfStatement";
- }
-
- function isNegatedUnaryExpression(test) {
- return test.type === "UnaryExpression" && test.operator === "!";
- }
-
- function isNegatedBinaryExpression(test) {
- return test.type === "BinaryExpression" &&
- (test.operator === "!=" || test.operator === "!==");
- }
-
- function isNegatedIf(node) {
- return isNegatedUnaryExpression(node.test) || isNegatedBinaryExpression(node.test);
- }
- return {
- IfStatement(node) {
- if (!hasElseWithoutCondition(node)) {
- return;
- }
- if (isNegatedIf(node)) {
- context.report({
- node,
- messageId: "unexpectedNegated"
- });
- }
- },
- ConditionalExpression(node) {
- if (isNegatedIf(node)) {
- context.report({
- node,
- messageId: "unexpectedNegated"
- });
- }
- }
- };
- }
- };
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